Distillation and cracking of oil



Dec. 15, 1931. w. MENDlUs y DISTILLATION AND CRACKING 0F OIL Filed June18, 1929 LAUMUUN Mv Z .You

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` Patented Dec. 15, 1931 UNITED STATES PATENT oI-FICEv `WILLIAM MENDIUS,OF CHICAGO, ILLINOIS, ASSIGNOR T SINCLAIR REFINING COM- PANY, 0F NEWYORK, N. Y., A CORPORATION 0F MAINE DIST'ILLATION-AND CRACKING- 0F OILAppuation mea :une 1s,

This invention relates to improvements 1n the manufacture of lowerboihng oils such as gasoline from higher boiling oils-suchA as gas oil,crude petroleums and reduced crude petroleums by cracking, toimprovements in the. manufacture of lubricating oils from crudepetroleums and reduced crude petroleums by vacuum distillation, and toimprovements in reducing to coke residual components of such crudestocks; more particularly the invention relates to a combined operationhaving several important advantages in the manufacture of lower boilingoils such as gasoline and inthe manufacture of lubricating oils and' inreducing residual stocks to coke.

According to the present invention, a residual stock is reduced to cokeby direct introduction into the oil to be coked of hot oil products froma vapor phase cracking operation, a crude stock containing lubricatingoil components is preheated by indirect heat exchange with hot oilproducts escaping from the coking operation and lubricating oil stock isvaporized from the thus preheated crude stock under sub-atmosphericpressure, and

residual stock from the vaporizing operation, in which the lubricatingoil stock is separated from the preheated crude stock, is supplied tothe coking operation. A gas oil stock is condensed from the hot oilproducts escaping from the coking operation and this condensed gas oilstock is supplied to the vapor phase cracking operation. The residualstock supplied'to the coking operation may include tar componentsseparated from A the. hot oil product escaping lfrom the cokingoperation as Well as the residual stock from the vaporizing operation inwhich the lubricating oil stock is separated from the preheated crudestock.

A number of advantages are thus secured. This combined operation makesuse ofheat available in the hotoil products from the vapor phasecracking operationto separate lubricating oil components from crudestocks in a particularly advantageous manner. In this combinedoperation, decomposition of lubricating oil components of the crudestock, as through local overheating, is reduced to a 1929. Serial N0.371,865.

minimum although residual components of the crude stock are reduced tocoke in the same operation. In this combined operation, lubricating oilstocks separated from the crude stock are not subjected to contaminationor deterioration through contact with lower boiling or reactivecomponents of the hot oil products discharged from the vapor phasecracking operation. In this combined operation, gas oil stocks or stockcomponents produced by coking of the residual stock from the vaporizingoperation are supplied directly to the vapor phase cracking operation.'The combined operation of the invention frequently makes possible anincreased recovery oflubricating oil stocks from the same crude stockWithout prejudice to the economy of the complete operation.v Althoughsevertl sub-operations are involved in this combined operation, theapparatus required for carrying out the operation may be made quitesimple.

The preheating of the crude stock supplied to the vaporizing operationmay b e effected, in

.carrying out the invention, in a number of Ways. This crude stock maybe preheated, for example, by indirect heat exchange with vapors orliquids in a'scrubbing operation for the separation of tar components towhich the hot oil products escaping from the coking operation aresubjected, by indirect heat exchange With the vapors escaping from sucha scrubbing operation, by indirect heat exchange with vapors or liquidsin or escaping from fractionating or condensing operations to whichvapors escaping from such a scrubbingv operation, or from the cokingoperation, are subjected, or by any combination of such several Ways.

The invention will be further described in connection With theaccompanying drawing which illustrates, diagrammatically andconventionally, one form of apparatus adapted for carrying out theinvention. It Will be understood that other and different apparatus maybe used.

In carrying out the combined voperation of the invention in theapparatus illustrated, the vapor phase cracking `operation is carriedout in the heater l, the preheating of the crude stock containing alubricating oil component is carried out in either the heat exchanger 2or the cooling coils of reiux condenser 3 or reflux condenser 4 or theheat exchange coil 5 (arranged in the scrubbing tower 10) or in acombination of these heat exchange means, the vaporizing operation forseparation of lubricating oil components from the preheated crude stockis carrled out in tower 6, operated under sub-atmospheric pressure, andthe coking operation is carried out in one or more of the cokingreceptacles 7, 8, etc.

The vapor phase cracking operation proper may be carried out, forexample, as described in application Serial No. 198,621 filed June 13,1927, by Harry L. Pelzer, and the hot vapor mixture from the digestingdrums discharged directly into the coking receptacles, or the digestingdrums may be omitted and the hot'vapor mixture from the heater properdischarged directly into the coking receptacles, as in the apparatusillustrated. In this apparatus, the vapor phase cracking operationproper is carried out in the heater 1 comprising a group of seriesconnected heating tubes arranged in the heating flue of a furnace 30, afan 31 being provided for circulating the heating gases through theheating fine, ducts 32 with dampers as shown being provided forrecirculating part of the heating gases through the heating ilue and fordischarging part of the heating gases to stack 33, and fan 34 andpreheater 35 arranged in the stack 33 being provided for supplyingpreheated air for combustion to the lirebox 36 of the furnace 30. Oil issupplied to the heater 1 through c'onnecton 37 and the hot oil productsof the vapor phase cracking operation carried out therein are dischargedthrough connection 38 to the coking receptacles.

A series of coking receptacles 7, 8, etc., is provided so that a cokingoperation, such as is described in application Serial No. 340,996, filedFebruary 18, 1929, by Harry L. Pelzer, may be carried out continuouslytherein, one or more of the series being in use for carrying out thecoking operation proper while others are shut down for discharge of thecoke product or for cleaning or repair. But two coking receptacles areshown to simplify the drawings. Such a series of coking receptacles maybe operated, for example, as described in application Serial No.341,213, filed February 19, 1929, by Harry L. Pelzer. One form of valvespecially adapted for making the change-over from one coking receptacleto another coking receptacle during operation is described inapplication Serial No. 342,904, filed February 26, 1929, by Eugene C.Herthel and Willis S. Gullette. The hot oil products from the vaporphase cracking operation are introduced into the coking receptacle 7 forexample, through connection 9. This connection 9 may be arran ed todischarge into the lower part of the co ing receptacle or as describedin application Serial No. 347,533, filed March 16, 1929, by Edward W.Isom and George H. Taber, Jr. Residual stock to be coked is su )plied tothe coking receptacle 7, for examp e, through connection 1l or throughconnections 11 and 12. Vapors escape from the coking receptacle 7 forexample, through connections 13 and 15.

The scrubbing tower 10 may, with advantage, be arranged and operated asdescribed in application Serial No. 345,199 filed March 7, 1929, byEugene C. Herthel. This scrubbing tower 10 comprises a lower, anintermediate and an upper part. The lower part is adapted formaintaining a liquid body of oil during operation normally submergingthe inlet connection 14 through which connection 15 from the cokingreceptacles discharges. The intermediate part is provided with openbaflies 16 and the upper part is provided with bubble plates 17.Residual stock is supplied from the liquid body in the lower part oftower 10 to the coking receptacles through connection 57 by means ofpump 58, to receptacle 7, for example, through connection 12. Theoperation of this tower is controlled by direct introduction of arefluxing medium or by means or" reflux condenser 4 or by both of thesemeans. Connection 18 is provided Jfor the introduction of a refluxingmedium into the upper part of the tower. Reflux condenser 4 is alsoprovided for supplying a refluxing medium to the upper part of thetower. Vapors escape from the upper part of tower 10 through connection19 to the lower part of tower 20. The heat exchange coil 5 (previouslymentioned) is arranged in the intermediate part of the tower 10.

The fractionating tower 20 may be of conventional bubble towerconstruction. This tower may be operated, for example, as described inapplication Serial No. 345,199, filed March 7, 1929, mentioned above.Connection 21 is provided Nfor supplying raw stock to the lower part ofthis tower. The operation of this tower may be controlled by means ofeither or both of the reflux condensers 3 and 23 or by the directintroduction of a reluxing medium through connection 22 or by both ofthese means. In the apparatus illustrated these reflux condensers areshown as arranged for the use of crude stocks supplied to the operationand gas oil stocks supplied to the operation, respectively, as coolingmedia. An extraneous cooling medium, such as water, may, however, beused in either of these reflux condensers. A direct reiuxing medium,such as a part of the cracked distillate product or a similar fraction,may be supplied to the upper part of tower 20 through connection 22 bymeans of pump 2A.

The vapors formin the cracked distillate product escape from t e upperpart of tower 20 through connection 25 to condenser 26` This condenseris arranged to discharge into the receiver and gas separator 27 fromwhich the condensed cracked distillate product is discharged throughconnection 28, uncondensed vapors and gases being discharged throughconnection 29.

The vaporization operation for the separation of lubricating oilcomponents from the crude stock supplied to the operation is carried outin vacuum tower 6. Crude stock is supplied to the operation throughconnection 39 by means of pump 40. This stock is preheated to atemperature at which the lubricating oil components are vaporized underthe pressure prevailing in the tower 6 by circulation through one ormore of the several heat exchange means previously mentioned, the heatexchanger 2', the heat exchange coils in the reflux condensers 3 and 4and the heat exchange coil 5 in the scrubbing tower l0,

. the heat exchange in every case being indirect.

The preheated crude stock is released into the lower part of tower 6through connection 41 including valve 42. In this tower lubricating oilcomponents of the crude stock are separated by vaporization from theremaining residual stock. The residual stock is supplied throughconnection 43 by means of pump 44 to the coking receptacles, to thecoking receptacle 7 through connection 11 for example. rllhe vaporizedlubricating oil components, or the lower boiling of these components,escape from the upper part of tower 6 through connection45 to condenser46. A hi her boiling lubricating oil fraction, a distllled bright stock,for example, may be condensed in the upper part of the tower 6 anddischarged through connection 47 and cooler 48. The operation of thistower may be controlled by regulation ,of the sub-atmospheric pressuremaintained therein, or by circulation of an extraneous cooling medium orof gas oil, or part of it, supplied to the combined operation throughthe heat exchange coil in the reflux condenser 59. Condenser 46 isarranged to discharge into receiver 49 and cooler 48 into receiver 50from which receivers the lubricating oil fractions are pumped by meansof pump 51 and pump 52, respectively. The required sub-atmosphericpressure is maintained in the vacuum tower 6 by means of an exhauster 53connected to the receivers 49 and 50 through connections 54 and 55,respectively.

The condensate or condensate mixture collecting in the lower part oftower 2O is supplied, by means of pump 56 through heat exchanger 2 andconnection 37, to the vapor phase cracking operation. This stockusugally of gas oil character, may consist exclu;

sively of components vaporized from the residual stock supplied to thecoking receptacles from the lower part of the tower 6, or from thisresidual stock and the residual stock supplied to the coking receptaclesfrom the liquid body maintained in the lower part of scrubbing towerV10. Or this stock may include, in addition to such components,additional gas oil components from gas oil supplied through connection60 by means of pump 61, to the lower part of tower 20 through connection21, or to the upper part of tower 10 through connection 18, vaporizedtherein and condensed in tower 20. Gas oil so supplied to the operationmay be used, in whole or in part, as a cooling medium either in thereflux condenser 59 for controlling the operation of the tower 6 or inthe vheat exchange coil 5. If additional heat is required, this crudestock, or part of it, may be circulated through the heat exchange coilin the reflux condenser 3. lf such heat exchange is insufficient tomaintain control of the scrubbing operation carried out in tower l0 orofthe fractionating operation carried out in tower 20, another stockcooling medium or an extraneous cooling medium is used or a directrefluxing medium is supplied to the operations. It will be understoodthat the requirements of diierent operations, the maintenance ofdifferent stockA balances, for example, may require variation of theprecise heat exchange scheme usedto combine the necessary preheating ofthe crude stock supplied to the vacuum tower 6 with the required controlof the scrubbing tower 10 and the fractionating tower 20. p Theinvention will be further illustratedY by the following more detailedexample oi" one operation embodyingu the invention as carried out in theapparatus illustrated:

Reduced crude,supplied by means of pump 40, is circulated successivelythrough the heat exchanger `2 and the heat exchange coil in therefluxcondenser 4-and thereby preheated to a temperature of about 650 F.and, at this temperature, the preheated reduced crude is released withinthe lower part .of the vacuum tower 6, the latter being maintainedVunder a pressure of about30 mm. of mercury absolute. ln the vacuum tower6, the larger part of the reduced crude, say 75%, is vaporizedv leavinga residual stock, 10 API for examf; ple, which is supplied to the cokingreceptacles by means of pump 44. The vaporized part of the preheatedreduced crude is collected as a lubricating o il fraction or fractionsin the receiver 49 or in the receivers 49 and 50. Gas oil characterstock is supplied from the lower part of tower 20 by means of pump 56through the heat exchanger 2 t0 the vapor phase cracking operationcarried out in heater l. Here this gas oil stock is heated, for example,to a temperature in the neighborhood or HOO-11500 F. under pressure justsuicient to maintain iow through the coking receptacles, the scrubbingtower 10, the fractionating tower 20 and the condenser 26 to receiver27, the latter being maintaind under atmospheric pressure or somepressure slightly above atmospheric pressure. In the cokinglreceptacles, 4the residual stock supplied from the vacuum tower 6,together with the residual stock supplied from the lower part of towerl0, is reduced to coke by direct heat exchange with the hot oil productsdischarged from the vapor phase cracking operation. The hot vapormixture from' the coking operation is discharged into and beneath thesurface of a liquid body of oil maintained in the lower part of tower 10and there stripped of tar components, the latter being returned to thecoking operation with residual stock from this liquid body, this liquidbody being maintained, for example, at a temperature in the neighborhoodof 725-775 F. In the fractionating tower 20, the gas oil 4components ofthe vapor mixture escaping from tower l0 are condensed to be supplied tothe heater l together with sufficient additional raw gas oil, suppliedthrough connection 60, to maintain the required supply of oil for thevapor phase cracking operation. This fractionating operation may becontrolled, for example, to effect the condensation of all components ofthe entering vapors higher boiling than suitable as components of thedesired distillate product, gasoline for example. The products of thecombined operation may thus comprise a gasoline or a gasoline fraction,a lubricating oil fraction or fractions and a coke product.

I `claim:

1. In an operation combining the separation of lubricating oilcomponents from crude stocks containing the same and the production of acracked distillate product, the improvement which comprises reducinresidual stock to coke by direct introduction into the oil to be cokedof hot oil products direct from a vapor phase cracking operation,heating a crude stock containing lubricating oil Y components byindirect heat exchange with hot oil products escaping from said cokingoperation, materially reducing the pressure below atmospheric pressureand vaporizing lubricating oil stock from the thus heated oil undersub-atmospheric pressure, and supplying residual stock from thesubatmospheric vaporizing operation to the coking operation.

2. In an operation combining the separation of lubricating oilcomponents :from crude stocks containing the same and the production ofa cracked distillate product, the improvement which comprises reducingresidual stock to coke by direct introduction into the oil to be cokedof hot oil products direct from a vapor phase cracking operation,heating a crude stock containing lubricating oil components by indirectheat exchange with hot oil products escaping from said coking operation,materially reducing the pressure below atmospheric pressure andvaporizing lubricating oil stock from the thus heated oil undersub-atmospheric pressure, supplying residual stock from thesubatmospheric vaporizing operation to the coking operation, condensinga gas oil stock from the hot oil products escaping from said cokingoperation and supplying such condensate to the vapor phase crackingoperation.

In testimony whereof I affix my signature.

